Just found this today, not sure what rock I've been living under that made me not find this yet. The ability to customize with the userChrome.css file is almost endless and only limited by your imagination and your google-fu. Keep up the good work!

It's good except a couple of glitches: sometimes plus button doesn't work, sometimes clicking on a tab opens other tab.

Can you
1) create an option to FULLY disable tree structure?
2) Add folders?
I just want to have vertical tabs, no any trees.

It is the best and the main reason I use firefox, but I have a problem, with new Themes for firefox, Tree background color changes based on which Theme I choose, is there any way I can keep original color or modify this color myself? with some Themes, color of tabs and their background becomes completely black or white !! so I can not even see tab's caption, thanks!

This is an awesome extension, on which I rely heavily in my daily workflows. But please, please make the tree structures saveable and shareable across firefox (desktop) sessions! Ideally, I would be very happy if TST could be made "compatible" with Session sync. It could be such a breakthrough for the daily workflows of many TST and Session sync users! (I have added the same comment to the Session sync developers too. I hope that there can be an "easy" solution to add tree info to the bookmarks used by Session sync, from which the whole tree can be built back easily by TST when a session is restored...) Thanks a lot!

Best extension hands down.

works well, and, is simiarly to the screenshots. If you like side tabs, this is a great add on.

This is an excellent, free tool. It's super handy for keeping my tabs organized. It has the occasional glitch, but I seem to be able to clear them by pressing F1 twice (to close the Tree Style Tab pane and reopen it).